This is the matchup is one which I am very familiar with and can go into the most detail with. First off, knowledge is your friend in this matchup, with all of your gitaxian probes and Thoughtseizes, you can figure out how long it will be until they can safely fire off a show and tell or sneak attack. Make sure not to use all these spells at once as you will want to know how they are doing as the game progresses. If they manage to resolve one of their two win conditions your chances to win are slim to none. Prioritize your counters on whatever they may need to assemble their win. If you know they are missing a piece, it is acceptable to counter brainstorms or ponders to prevent them from digging. If they only get to see one card a turn and you have a resolved threat the game heavily turns in your favor. Lay as much pressure on them as you can while trying to pick their hand of either fatties or cheat-into-play cards.
Boarding:
Your direct removal is useless here so take that shit out (3 cards). You are left with only your edicts to handle their resolved threats should one of them hit the board. Now the current sideboard doesn’t have that much play with sneak and show as our main deck already has a lot of the key elements for this matchup (discard, knowledge, denial). The best thing we can do here is bring in more of what works (Force of Wills, Diabolic Edicts, Hymn to Tourachs, and Misdirection (not entirely happy with this spell here, but being to win counter wars is vital)). Also if you have it in the board, Surgical Extraction]] can neuter (Cut their chance of going off in about 50%) S&S turn one if you happen to Thoughtseize away either Sneak Attack or Show and Tell, so there is merit to running that in the board over leyline of the void (more than likely I will make that change as SE allows you to fight the non-interactive combo decks more efficiently).
Post Board:
There are a few things in this matchup that can cause problems for us here. Boseiju, Who Selters All and Defense Grid may pop up and prevent us from countering their threats. Holding your Wastelands for the land and countering/making them discard the Grid is a must here. Using up counters and discard in this way isn’t ideal, but being able to interact with the S&S player is an absolute must. In some cases you may see Blood Moon come out. Depending on how far along the game is you may or may not have to worry about this. If you have a resolved Delver of Secrets
Flip or Death's Shadow at this point, and are keeping up pressure, you have the option of just leaning on a force (if you have it) to prevent them from resolving cheaty-spell.
